In reservoir injection systems, a high-pressure pump propels the fuel to be injected from a tank into a central high-pressure fuel reservoir (rail). From this rail, individual fuel lines lead to the respective injectors of the cylinders of the internal combustion engine. The injectors are triggered individually as a function of the engine operating parameters of the internal combustion engine in order to inject fuel into the respective combustion chamber. FIGS. 3 and 4 show a high-pressure fuel reservoir according to the prior art. As can be seen in the figures, the high-pressure fuel reservoir comprises a base body 1 which has a longitudinal bore 3, from which there branch off a plurality of connection bores 2 for the injectors. Since the reservoir injection systems operate at very high pressures, strength problems occur in particular at the transitional areas, indicated by arrows in FIG. 3, between the longitudinal bore 3 and the connection bores 2, which problems lead to cracks there which rapidly become enlarged. For this reason, very expensive, highly resistant materials are used for the base body 1 in the prior art, and complex and time-consuming aftertreatment steps are performed at the points at risk from cracking, such as e.g. deburring or shot peening. As a result, the known high-pressure fuel reservoirs are very labor-intensive and expensive to manufacture.
DE-199 45 786 C1 also discloses a high-pressure fuel reservoir in which an inner chamber is formed from two circular cylindrical recesses which are disposed parallel to each other in the longitudinal direction and are connected to each other. In this arrangement the connection bores for the injectors are disposed in a connection area which is provided between the two longitudinal bores and is in the form of a saddle. By this means favorable stress ratios can be generated at the transitional area between the longitudinal bore and the connection bore. This high-pressure fuel reservoir does, however, have a relatively large width due to the parallel arrangement of the two longitudinal bores. Moreover, the manufacture of the two parallel bores, e.g. by means of deep-hole drilling, is very complex and expensive.